Meaning
Engineered composite films composed of alternating sub-nanometer layers of different materials, typically deposited by atomic layer deposition. In semiconductor manufacturing, nanolaminates are used to combine the desirable dielectric and mechanical properties of different oxides while suppressing the growth of crystalline defects. These layered structures provide high dielectric strength and low leakage currents for advanced transistor passivation.
Barrier Capability
Alternating layers of amorphous and crystalline oxides prevent the propagation of grain boundaries through the thickness of the film. This grain-boundary disruption inhibits the diffusion of moisture, which improves the environmental protection of the underlying layers.
Electrical Performance
The dielectric constant and breakdown voltage of these layered materials can be tuned by adjusting the ratio of the constituent layers. Mixing a high-permittivity oxide with a high-bandgap oxide yields a composite that exhibits both high capacitance and high breakdown strength. This combination of properties is necessary for gate dielectrics and high-voltage passivation layers that must resist electric-field breakdown.
Deposition Control
Precise execution of the growth process requires the alternate exposure of the substrate to different precursor gases in a sequential cycle. Controlling the pulse and purge times prevents gas-phase reactions, ensuring that each interface is atomically abrupt and free of chemical contamination. This level of control allows for the uniform coating of complex, high-aspect-ratio transistor geometries.
By monitoring the growth rate per cycle in real-time using spectroscopic ellipsometry, operators can verify that the layer thicknesses match the target design down to the angstrom scale.
